In a large bowl, mix together the butter, caster sugar and cinnamon until creamy. Add the beaten egg and flour, mixing together until a dough forms.
Gather the dough into a ball and chill for 30 minutes. On a lightly floured surface, roll out the dough to ½cm thick, then cut into 3 different sizes of stars using cutters or triangles, using a knife if you don’t have cutters.
Place on separate baking trays, according to size. Bake in a preheated oven at 200°C, fan 180°C, gas 6 for 12-14 minutes, then leave to cool.
Stack into trees using 3 large, 2 medium and 2 small stars or triangles, using a writing icing tube to stick them together. Dust with icing sugar and use the writing icing tube to stick on decorating balls for Christmas baubles.